Coated hollow polyester molding, method of reclaiming the same, and solution for surface coating

ABSTRACT

To provide a polyester hollow molded product which eliminates the possibility of contaminating its contents, retains excellent transparency after it is used repeatedly by recycling and can be re-used with a substantially unscratched surface. The polyester hollow molded product has a polyester coating layer on the exterior surface and the coating layer can be removed with hot water or alkaline aqueous solution.

FIELD OF THE INVENTION

The present invention relates to a coated polyester hollow moldedproduct, a regeneration method and a surface coating solution therefor.More specifically, it relates to a coated polyester hollow moldedproduct having a coating film which can be easily removed withoutexerting a bad influence on the polyester hollow molded product, aregeneration method therefor and a surface coating solution for formingthe coating film.

PRIOR ART

A polyethylene naphthalene dicarboxylate-based (may be abbreviated asPEN hereinafter) hollow molded product has more excellent characteristicproperties than a polyethylene terephthalate-based (may be abbreviatedas PET hereinafter) hollow molded product and is expected as a hollowmolded product which can be salvaged and recycled.

The cleaning of a hollow molded product is necessary for recycling andgenerally carried out using an aqueous solution (1 to 6%) of sodiumhydroxide heated at 50 to 1000° C.

However, when alkali cleaning is made on a PEN-based hollow moldedproduct salvaged after use, the transparency of the hollow moldedproduct reduces. The reduction of transparency is more marked as thenumber of times of salvaging and recycling increases.

Although water resistance can be provided simply by coating the surfaceof the PEN-based hollow molded product, it is difficult to remove thecoating layer for recycling, for example, the coating layer can not beremoved by cleaning with hot water.

When an ultraviolet light absorbing compound is blended with a materialfor the hollow molded product without forming a coating layer, such aproblem as the contamination of contents by a bleed-out may arise.

Further, as the PEN-based hollow molded product has high surfacehardness, its surface is easily scratched and the scratching of thesurface must be suppressed for salvaging and recycling.

Meanwhile, the following publications are known for water-solublepolyesters.

JP-A 10-110027 (the term “JP-A” as used herein means an “unexaminedpublished Japanese patent application”) discloses a method of producinga hot water-soluble polyester by esterifying or carrying out an esterexchange reaction among terephthalic acid, alkali metal sulfonategroup-containing aromatic dicarboxylic acid or lower alkyl ester thereofand ethylene glycol, and melt polycondensing and solid-phasepolymerizing the esterified product or the product of the ester exchangereaction. The above publication teaches that the produced hotwater-soluble polyester can be used as a material for forming a patternby dissolving a required portion with hot water after the formation of afabric.

JP-A 8-176284 discloses a water-soluble polyester which contains an iondissociable group-containing dicarboxylic acid component and/or an iondissociable group-containing glycol component in the molecular mainchain of the polyester in an amount of 51 mol % or more based on thetotal of all the acid components, is produced at a polymerizationtemperature of 1800° C. or higher and lower than 2400° C. and has anintrinsic viscosity measured in orthochlorophenol at 350° C. of 0.25 ormore. The above publication teaches that this water-soluble polyester isuseful for the production of a low charged adherent polyester film whichis useful for package materials, magnetic cards, magnetic tapes,magnetic disks, printing materials and the like.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a coated polyesterhollow molded product which eliminates the possibility of contaminatingits contents, retains excellent transparency even after it is salvagedand recycled and can be recycled with substantially no scratchedsurface.

It is another object of the present invention to provide a surfacecoating solution which is used for the production of the coatedpolyester hollow molded product of the present invention.

It is still another object of the present invention to provide a methodof regenerating the coated polyester hollow molded product of thepresent invention for recycling.

Other objects and advantages of the present invention will becomeapparent from the following description.

According to the present invention, firstly, the above objects andadvantages of the present invention are attained by a coated polyesterhollow molded product comprising:

(A) a polyester hollow molded product, and

(B) a polyester coating layer formed on the exterior surface of thehollow molded product.

According to the present invention, secondly, the above objects andadvantages of the present invention are attained by a surface coatingsolution for a polyester hollow molded product, which contains 1 to 40wt % of a polyester comprising 92.99 to 60 mol % of at least onedicarboxylic acid unit selected from the group consisting of naphthalenedicarboxylic acid unit and terephthalic acid unit, 0.01 to 20 mol % ofan isophthalic acid unit and 7 to 20 mol % of an isophthalic acid unithaving a sulfonic acid metal salt group based on the total of all thedicarboxylic acid units as dicarboxylic acid components, and 65 to 95mol % of an ethylene glycol unit and 35 to 5 mol % of a diethyleneglycol unit based on the total of all the diol units as diol units, 0.1to 10 wt % of a surfactant and a liquid medium.

According to the present invention, thirdly, the above objects andadvantages of the present invention are attained by a method ofregenerating a coated polyester hollow molded product comprising thesteps of preparing the salvaged coated polyester hollow molded productof the present invention, removing a polyester coating layer for thehollow molded product and forming anew polyester coating layer on thesurface of the hollow molded product from which the polyester coatinglayer has been removed.

The present invention will be described in detail hereinbelow.

A description is first given of the coated polyester hollow moldedproduct of the present invention. The polyester hollow molded product(A) constituting the coated polyester hollow molded product comprisespreferably an aromatic polyester, more preferably an aromatic polyesterwhich comprises a recurring unit selected from the group consisting ofethylene-2,6-naphthalene dicarboxylate unit and ethylene terephthalateunit in an amount of at least 85 mol % based on the total of all therecurring units. The aromatic polyester may be used alone or blendedwith two or more types of another aromatic polyester.

Polyethylene terephthalate and polyethylene-2,6-naphthalenedicarboxylate are particularly preferred as the aromatic polyester.

The intrinsic viscosity of the aromatic polyester is preferably 0.5 to1.0, more preferably 0.55 to 0.8, particularly preferably 0.55 to 0.75.When the intrinsic viscosity is lower than 0.5, blowing propertiesworsen, thereby making it difficult to obtain a molded product having auniform thickness. When the intrinsic viscosity is higher than 1.0,elongation stress becomes high, which might be the cause of hazing amolded product.

The polyester hollow molded product made from the above polyester can beproduced by employing a known general molding technique. Examples of theapplicable molding method include biaxial orientation blow moldingtechniques (cold parison method and hot parison method), injection blowmolding technique and direct blow molding technique. In addition, amolding technique in which a hollow molded product is formed after thepolyester is molded into a sheet form may be used. The polyester hollowmolded product may be a bottle.

Preferably, the polyester coating layer (B) formed on the exteriorsurface of the polyester hollow molded product has a weight reduction of3 wt % or less when it is treated with 25° C. water for 2 hours and isremoved when it is treated with an alkali aqueous solution having atemperature of 750° C. and a pH of 11.6 for 9 minutes.

When the weight reduction is 3 wt % or less after 2 hours of a treatmentwith 250° C. water, the polyester hollow molded product is circulated inthe market and used as a vessel and the coating layer is substantiallyretained even after it contacts water during this. When the weightreduction is larger than 3 wt %. the coating layer substantially fallsoff or peels off from the hollow molded product, thereby causing anappearance problem. The weight reduction is more preferably 2 wt % orless.

The coating layer can be easily removed from the polyester hollow moldedproduct circulated and used as a vessel under alkali conditions in thecleaning step when it is treated with an alkali aqueous solution havinga temperature of 75° C. and a pH of 11.6 for 9 minutes. When the coatinglayer can be removed with an alkali aqueous solution under suchconditions, the coating layer can be removed with hot water heated at 60to 100° C., preferably 70 to 95° C. and a pH of 5.5 to 8.5, preferably 6to 8 in most cases.

The preferred polyester coating layer (B) having the above properties ismade from a polyester which comprises 92.99 to 60 mol % of at least onedicarboxylic acid unit selected from the group consisting of naphthalenedicarboxylic acid unit and terephthalic acid unit, 0.01 to 20 mol % ofan isophthalic acid unit and 7 to 20 mol % of an isophthalic acid unithaving a sulfonic acid metal salt group based on the total of all thedicarboxylic acid units as dicarboxylic acid components and 65 to 95 mol% of an ethylene glycol unit and 35 to 5 mol % of a diethylene glycolunit based on the total of all the diol units as diol units.

Examples of the naphthalene dicarboxylic acid unit include2,6-naphthalene dicarboxylic acid and 2,7-naphthalene dicarboxylic acid,out of which 2,6-naphthalene dicarboxylic acid is particularlypreferred.

The naphthalene dicarboxylic acid unit and the terephthalic acid unitmaybe derived from an ester derivative. Examples of the ester derivativeinclude methyl esters, ethyl esters, propyl esters and butyl esters, outof which methyl esters are preferred.

The amount of at least one unit selected from naphthalenedicarboxylidacid unit and terephthalic acid unit is 60 to 92.99 mol % based on thetotal of all the dicarboxylic acid components. When the amount issmaller than 60 mol %, the water resistance of the polyester lowers andwhen the amount is larger than 92.99 mol %, the solubility in hot waterof the polyester deteriorates. Further from the viewpoint of solubilityin hot water, the amount of the naphthalene dicarboxylic acid unit ispreferably 50 mol % or less based on the total of all the dicarboxylicacid components.

The amount of the naphthalene dicarboxylic acid unit is preferably 0 to50 mol %, more preferably 0 to 30 mol %, particularly preferably 0 to 10mol % based on the total of all the dicarboxylic acid components toobtain excellent solubility in hot water.

Examples of the isophthalic acid unit include isophthalic acid andderivatives thereof such as methyl, ethyl, propyl and butyl esters.

The amount of the isophthalic acid unit is 0.01 to 20 mol %, preferably0.01 to 15 mol %, particularly preferably 5 to 10 mol % based on thetotal of all the dicarboxylic acid components. When the amount issmaller than 0.01 mol %, the crystallinity of the polyester becomes toohigh. When the amount is larger than 20 mol %, reductions inpolymerization reactivity and crystallinity become large.

Examples of the isophthalic acid unit having a sulfonic acid metal saltgroup include 5-lithium sulfoisophthalic acid, 5-sodium sulfoisophthalicacid and 5-potassium sulfoisophthalic acid, out of which 5-sodiumsulfoisophthalic acid is particularly preferred.

They may be derived from a derivative. Examples of the derivativeinclude esters such as methyl esters, ethyl esters, propyl esters andbutyl esters, out of which methyl esters are particularly preferred.

The amount of the isophthalic acid unit having a sulfonic acid metalsalt group is 7 to 20 mol %, preferably 8 to 15 mol %, particularlypreferably 9 to 13 mol % based on the total of all the dicarboxylic acidcomponents. When the amount is smaller than 7 mol %, solubility in hotwater becomes insufficient and when the amount is larger than 20 mol %,reactivity at the time of polymerization deteriorates and melt viscositybecomes too high, thereby reducing productivity.

The amount of the ethylene glycol unit is 65 to 95 mol % based on thetotal of all the diol components.

The amount of the diethylene glycol unit is 5 to 35 mol %, preferably 10to 35 mol %, particularly preferably 10 to 25 mol % based on the totalof all the diol components. When the amount is smaller than 5 mol %,solubility in hot water lowers and when the amount is larger than 35 mol%, deterioration caused by thermal decomposition becomes large.

The diethylene glycol unit may be derived from a diethylene glycolcomponent which is added at the time of polymerization or may beproduced by a polymerization reaction.

The polyester of the polyester coating layer (B) is particularlypreferably a polyester which comprises the isophthalic acid unit havinga sulfonic acid metal salt group in an amount of 8 to 15 mol % based onthe total of all the dicarboxylic acid units and the ethylene glycolunit in an amount of 75 to 95 mol % based on the total of all the diolunits.

The polyester has an intrinsic viscosity of preferably 0.2 to 0.5, morepreferably 0.25 to 0.45. When the intrinsic viscosity is lower than 0.2,chipping at the time of polymerization becomes difficult and strengthbecomes low disadvantageously. When the intrinsic viscosity is higherthan 0.5, productivity at the time of polymerization lowers andsolubility in hot water deteriorates disadvantageously.

The glass transition temperature of the polyester is preferably in therange of 55 to 90° C.

Out of the above polyesters for the polyester coating layer (B), apolyester having the following properties (1), (2) and (3) can increasethe functionality of the polyester coating layer (B) because iteliminates the possibility of contaminating the contents of the hollowmolded product and can retain excellent transparency and a substantiallyunscratched surface even when the hollow molded product is salvaged andrecycled;

(1) a solubility in water heated at 95° C. of 10 wt % or more,

(2) a solubility in water heated at 30° C. of 1 wt % or less, and

(3) a reduction in intrinsic viscosity after 1 hour of a treatment withwater heated at 95° C. of 0.01 at maximum.

The polyester can be produced by the following method. For example, itcan be produced by esterifying or carrying out an ester exchangereaction among terephthalic acid or ester forming derivative thereof(preferably dimethyl ester), isophthalic acid or ester formingderivative thereof (preferably dimethyl ester), isophthalic acid havinga sulfonic acid metal salt group or ester forming derivative thereof(preferably dimethyl ester), 2,6-naphthalene dicarboxylic acid or esterforming derivative thereof (preferably dimethyl ester) and ethyleneglycol (diethilene glycol is added as the case may be) under heating.

In the case of the ester exchange reaction, a cobalt, manganese,calcium, magnesium and/or titanium compound may be used as a catalyst.

To control reactivity and the content of diethylene glycol, an alkalimetal is preferably added. The alkali metal is preferably lithium,sodium or potassium. Out of these, sodium is preferred. The amount ofthe alkali metal is preferably 10 to 400 mmols, more preferably 100 to250 mmols based on 100 mols of the total of all the dicarboxylic acidcomponents.

Subsequently, a polycondensation reaction is carried out under heatingand vacuum in the presence of a germanium, antimony and/or titaniumcatalyst(s) and a phosphorus compound.

The phosphorus compound is preferably an inorganic phosphoric acid suchas phosphoric acid, hypophosphorous acid or phosphorous acid, or organicphosphoric acid such as trimethyl phosphate.

As desired, the polymer is then formed into a chip, pellet or block andground before use.

The coating layer can be formed by applying a liquid coating solutioncontaining this surface coating polyester to at least the exteriorsurface of the polyester hollow molded product and drying it.

A description is subsequently given of the surface coating solution.

The surface coating solution of the present invention contains thesurface coating polyester in an amount of 1 to 40 wt %. When the amountis smaller than 1 wt %, film formation is difficult and when the amountis larger than 40 wt %, the viscosity of the solution becomes high,thereby making it difficult to handle the solution.

According to the present invention, there is provided a solution whichcontains 1 to 40 wt % of a specific polyester, 0.1 to 10 wt % of asurfactant and a liquid medium as a preferred surface coating solutionas described above.

The surfactant may be ionic or nonionic. Preferably, it is polyethyleneglycolorpolyoxyethylene sorbitan alkylate. These surfactants arepreferably used in combination. That is, in a preferred aspect of thepresent invention, the surfactant is a mixture of polyethylene glycoland polyoxyethylene sorbitan alkylate in a weight ratio of preferably10:1 to 1:5, more preferably 10:1 to 1:2 from the viewpoints of filmforming properties at the time of coating and water resistance.

The surface coating solution of the present invention contains thesurfactant in an amount of 0.1 to 10 wt %, preferably 0.1 to 5 wt %.When the surfactant is contained in the above range, wettability at thetime of applying the coating solution for forming a coating layerbecomes satisfactory and the removal of the formed coating layer withhot water or the removal of the coating layer with an alkali aqueoussolution becomes easy. When the amount is larger than 10 wt %,solubility in normal temperature water increases.

The polyethylene glycol is preferably liquid with a low viscosity,particularly preferably liquid with a molecular weight of 200 to 1,000.

The polyoxyethylene sorbitan alkylate is preferably polyoxyethylenesorbitan oleate, polyoxyethylene sorbitan stearate or polyoxyethylenesorbitan palmitate, particularly preferably polyoxyethylene sorbitanoleate.

The surface coating solution is preferably a water solution or waterdispersion prepared by dissolving or dispersing the above components inwater. For dissolution or dispersion, hot water, preferably hot waterheated at 60 to 100° C. is desirably used from the viewpoints ofsanitation and handling safety.

In the case of a water solution, the surface coating polyester isdissolved in hot water, preferably hot water heated at 60 to 100° C., inpreferably 20 hours or less, more preferably 10 hours or less,particularly preferably 3 hours or less. This is aimed to suppresshydrolysis. The amount of the surface coating polyester is preferably 1to 40 wt %, more preferably 5 to 20 wt %. The amount is suitablycontrolled to this range by a coating method or the thickness of acoating film. When the amount of the surface coating polyester issmaller than 1 wt %, the thickness of the coating film is small andnonuniform disadvantageously. When the amount is larger than 40 wt %,the amount of the residual polyester undissolved in hot water increases,the viscosity of the solution rises, and coatability deterioratesdisadvantageously.

As a dispersing means, the surface coating polyester is dissolved in anorganic solvent such as ethanol, methanol, isopropyl alcohol,chloroform, acetone, methyl ethyl ketone or ethyl acetate in a highconcentration and mixed with water.

In either one of the cases of a water solution and a water dispersion,the surfactant may be contained in the surface coating solution and maybe added in any stage.

The surface coating solution of the present invention preferably has ahaze value at 25° C. of 30% or less, a pH of more than 5 and less than7, a viscosity of 0.5 Pa-s or less and an electric conductivity of 100to 4,000 μS/cm.

The surface coating solution of the present invention may contain atleast one agent selected from the group consisting of an ultravioletlight absorbent and colorant.

The surface coating solution of the present invention is novel as asolution for coating the surface of a polyester hollow molded product.

Therefore, according to the present invention, there is further provideduse of the surface coating solution of the present invention whichcomprises 1 to 40 wt % of the above specific polyester, 0.1 to 10 wt %of a surfactant and a liquid medium for coating a polyester hollowmolded product.

The coating layer formed by using the surface coating solution of thepresent invention provides the effects of preventing the exteriorsurface of a hollow molded product from being scratched, burying a smallscratch and preventing the appearance from being marred. Further, it hasthe ability of absorbing ultraviolet radiation and provides the effectof suppressing the deterioration of the polyethylene naphthalenedicarboxylate of the polyester hollow molded product by ultravioletradiation when it is used, salvaged and kept.

The haze value of the barrel portion of the polyester hollow moldedproduct having this coating layer of the present invention is preferably5% or less, more preferably 2% or less at a thickness of 300 μm. Whenthe haze value is larger than 5%, transparency is low and the appearanceas one of the values of a commercial product is marred if the polyesterhollow molded product is used as a bottle to be filled with a drink.

The thickness of the coating layer is preferably 0.1 to 10 μm, morepreferably 0.1 to 5 μm, much more preferably 0.2 to 2 μm. When thethickness is smaller than 0.1 μm, an optical deterioration suppressioneffect obtained by coating the surface of the hollow molded product islow disadvantageously. When the thickness is larger than 10 μm, theremoval of the coating layer with hot water or an alkaline aqueoussolution takes long disadvantageously.

The coating layer may include in an amount of 5 to 50 parts by weightbased on 100 parts by weight of the polyester, derived from thesurfactant contained in the coating solution.

In the present invention, this coating layer is renewed by removal andregeneration each time the polyester hollow molded product is re-used.

Therefore, according to the present invention, as described above, thereis provided a method of regenerating a coated polyester hollow moldedproduct comprising the steps of preparing the salvaged coated polyesterhollow molded product of the present invention, removing a polyestercoating layer from the hollow molded product, and forming a newpolyester coating layer on the surface of the hollow molded product fromwhich the polyester coating layer has been removed.

The step of removing the coating layer is preferably a step includingcleaning with heated water or alkaline aqueous solution and cleaningwith water thereafter.

For cleaning with heated water or alkaline aqueous solution, thetemperature of the water or alkaline aqueous solution used for removingthe coating layer is preferably 60 to 100° C., more preferably 65 to 95°C. When the temperature is lower than 600° C., satisfactory cleaningcannot be carried out, the coating layer cannot be completely removedand a further a sterilizing effect cannot be expected disadvantageously.When the temperature is higher than 100° C., the thermal deformation ofthe polyester hollow molded product is caused disadvantageously. Whenthe alkaline aqueous solution is used, sodium hydroxide is preferablyused in a concentration of 1 to 6%.

For cleaning with heated water or alkaline aqueous solution, thepolyester hollow molded product is preferably immersed in the aboveheated water or alkaline aqueous solution. As the case may be, theheated water or aqueous solution may be sprayed onto the polyesterhollow molded product.

For cleaning with water after cleaning with heated water or alkalineaqueous solution, water heated at 95° C. or less is preferably used.This cleaning may be carried out to such an extent that the alkalineaqueous solution is washed away completely.

In the present invention, the coating layer is renewed by forming a newcoating layer on the polyester hollow molded product from which thecoating layer has been removed so as to regenerate the polyester hollowmolded product. The method of forming this coating layer may be themethod of forming a coating layer when a polyester hollow molded productis to be produced. To this end, the surface coating solution of thepresent invention is preferably used.

The renewal of the coating layer is preferably carried out each time thepolyester hollow molded product is re-used. That is, each time it isre-used, it is preferably used to apply such a method that the polyesterhollow molded product is regenerated by the above regeneration method.

The polyester hollow molded product can be used repeatedly by renewingthe coating layer by this regeneration method and the haze of a barrelportion having a thickness of 300 μm when the polyester hollow moldedproduct is used 20 times repeatedly can be adjusted to 5% or less,preferably 2% or less. When it is used repeatedly, the polyester hollowmolded product is exposed to the ultraviolet radiation of the sunlightand the exposed dose of ultraviolet radiation having a wavelength rangeof 310 to 400 nm is estimated at 7,500 mJ/cm² to 90,000 mJ/cm² for onetime of use.

EXAMPLES

The following examples are given to further illustrate the presentinvention. The characteristic properties were measured by the followingmethods.

(1) Solubility

The time required for the dissolution of the surface coating polyesterfor the preparation of the surface coating solution was measured.

(2) Coatability

The surface coating solution was applied to a PEN film and wettabilityat this point was evaluated. Further, after coating, the coatingsolution was dried naturally to form a coating layer and the surfacestate of the coating layer was evaluated.

(3) Stability

The surface coating solution was dried by an evaporator to obtain solidmatter and its intrinsic viscosity was measured and taken as the initialintrinsic viscosity. The surface coating solution of Reference Example 1was maintained at 100° C. for 2 hours and dried by an evaporator toobtain solid matter and its intrinsic viscosity was measured and takenas the final intrinsic viscosity.

The following equation was used to calculate the stability of thesurface coating solution.

stability (%)=100 (%)×(initial intrinsic viscosity−final intrinsicviscosity)/(initial intrinsic viscosity)

(4) Intrinsic Viscosity

180 mg of a sample was dissolved in a mixed solvent of phenol andtetrachloroethane (3:2) and its intrinsic viscosity was measured by anUbbellohde viscometer tube at 250° C. The Huggins' constant ofpolyethylene terephthalate was used.

(5) Preparation of Test Sample

A 4 cm×4 cm test sample was cut out from the barrel portion of a bottle(thickness of about 300 μm). When the test sample had a surface coatinglayer, the test sample was cut out together with the surface coatinglayer.

(6) Exposure to Ultraviolet Radiation

The test sample was exposed to ultraviolet radiation using a xenontester (XW-150 Shimadzu xenon tester) for 4 hours.

(7) Exposed Dose of Ultraviolet Radiation

The ultraviolet radiation (250 to 310 nm, 310 to 400 nm) exposed dose ofthe test sample was measured by the UM-10 ultraviolet intensitometer ofMINORUTA Co., Ltd. (UM-250 photodetector, 360).

(8) Cleaning

The test sample was cleaned by immersing in a 1.8% NaOH aqueous solution(pH of 11.6) at 75° C. for 9 minutes, further cleaned with water anddried.

(9) Haze

The test sample was set in a turbidimeter (MODEL 1001DP color and colordifference meter of Nippon Denshoku Kogyo Co., Ltd.) to measure itshaze.

Example 1 Preparation of Surface Coating Polyester and Surface CoatingSolution)

An ester exchange reaction among 100 parts by weight of dimethylterephthalate (may be abbreviated as DMT hereinafter), 19 parts byweight of dimethyl 5-sodium sulfoisophthalic (may be abbreviated as K2hereinafter), 12.5 parts by weight of dimethyl isophthalate (may beabbreviated as DMI hereinafter) and 72 parts by weight of ethyleneglycol (may be abbreviated as EG hereinafter) was carried out in thepresence of manganese acetate and sodium acetate as catalysts whileby-produced methanol was distilled off to the outside of a system andthe temperature was raised to 250° C., antimony trioxide was added as apolymerization catalyst when the distillation of methanol was almostcompleted, and trimethyl phosphate was then added as a stabilizer toterminate the ester exchange reaction. Thereafter, the reaction productwas polycondensed under high temperature and high vacuum to obtain apolymer having an intrinsic viscosity of 0.40 (mixed solvent of 2 partsby weight of tetrachloroethane and 3 parts by weight of phenol, 25° C.).This polymer was formed into strand-like chips as surface coatingpolyester A.

This surface coating polyester A was dissolved in 95° C. hot water to aconcentration of 10 wt %, 2 wt % of polyethylene glycol having amolecular weight of 200 and 0.5 wt % of polyoxyethylene sorbitan oleatewere added to the obtained solution to prepare a surface coatingsolution under conditions shown in Table 1. This surface coatingsolution was evaluated. The results are shown in Table 1 and Table 2.The coating layer formed by using this surface coating solution did notdissolve in 35° C. hot water and did not peel off.

TABLE 1 sodium content temperature dissolution DMT DMI K2 NDC* acetateintrinsic of DEG* of hot water time stability (mol %) (mol %) (mol %)(mol %) (mol %) viscosity (mol %) (° C.) (min) (%) Ex. 1 80 10 10 0 2000.40 11 95 20 15 Ex. 2 80 10 10 0 100 0.30 19 95 30 20 Ex. 3 79 10 11 00 0.22 25 75 60 15 Ex. 4 90 0 10 0 150 0.40 10 90 40 15 Ex. 5 80 5 15 0200 0.44 18 80 60 25 Ex. 6 77 15 8 0 150 0.38 11 95 45 8 Ex. 7 80 0 1010 150 0.21 12 95 50 10 Ex. 8 75 10 15 10 200 0.44 18 85 60 18 Ex. 9 7010 10 10 200 0.39 14 95 50 10 Ex. 10 45 15 10 30 100 0.25 22 95 50 10Ex. 11 45 10 15 30 150 0.32 15 95 40 10 Ex. 12 25 13 12 50 100 0.31 25100 60 10 Ex.: Example *NDC: naphthalene-2,6-dicarboxylate *DEG:diethylene glycol

Examples 2 to 12

A surface coating polyester having composition shown in Table 1 wasobtained in the same manner as in Example 1 to prepare a surface coatingsolution under conditions shown in Table 1 and Table 2. This surfacecoating solution was evaluated. The results are shown in Table 1 andTable 2.

In any example, the coating layer formed by using the surface coatingsolution did not dissolve in 35° C. hot water and did not peel off.

TABLE 2 surface surfactant wettability state Ex. 1 2 wt % ofpolyethylene glycol 0.5 wt % of polyoxyethylene ∘ ∘ (molecular weight of200) sorbitan oleate Ex. 2 2 wt % of polyethylene glycol   1 wt % ofpolyoxyethylene ∘ ∘ (molecular weight of 300) sorbitan oleate Ex. 3 2 wt% of polyethylene glycol — ∘ ∘ (molecular weight of 300) Ex. 4 —   1 wt% of polyoxyethylene ∘ ∘ sorbitan oleate Ex. 5 2 wt % of polyethyleneglycol 0.5 wt % of polyoxyethylene ∘ ∘ (molecular weight of 200)sorbitan oleate Ex. 6 2 wt % of polyethylene glycol 0.5 wt % ofpolyoxyethylene ∘ ∘ (molecular weight of 200) sorbitan oleate Ex. 7 2 wt% of polyethylene glycol 0.5 wt % of polyoxyethylene ∘ ∘ (molecularweight of 200) sorbitan oleate Ex. 8 2 wt % of polyethylene glycol 0.5wt % of polyoxyethylene ∘ ∘ (molecular weight of 200) sorbitan oleateEx. 9 2 wt % of polyethylene glycol 0.5 wt % of polyoxyethylene ∘ ∘(molecular weight of 200) sorbitan oleate Ex. 10 2 wt % of polyethyleneglycol 0.5 wt % of polyoxyethylene ∘ ∘ (molecular weight of 200)sorbitan oleate Ex. 11 2 wt % of polyethylene glycol 0.5 wt % ofpolyoxyethylene ∘ ∘ (molecular weight of 200) sorbitan oleate Ex. 12 2wt % of polyethylene glycol 0.5 wt % of polyoxyethylene ∘ ∘ (molecularweight of 200) sorbitan oleate Ex.: Example wettability: ∘ means thatsurface cissing is rare and uniform coating is possible. surface state:∘ means that the dried surface is uniformly coated.

Reference Examples 1 to 5 Production of Polyesters

Polyesters for the polyester hollow molded product were produced by themethods of the following Reference Examples 1 to 5.

Reference Example 1

An ester exchange reaction between 100 parts by weight of2,6-naphthalene dicarboxylic acid dimethyl ester and 70 parts by weightof ethylene glycol was carried out in the presence of cobalt acetate,calcium acetate and magnesium acetate as ester exchange catalysts whilethe by-produced methanol was distilled off to the outside of a systemand the temperature was increased to 250° C., germanium acetate wasadded as a polymerization catalyst when the distillation of methanol wasalmost completed and trimethyl phosphate was then added as a stabilizerto terminate the ester exchange reaction. Thereafter, the reactionproduct was polycondensed under high temperature and high vacuum toobtain a prepolymer having an intrinsic viscosity of 0.50 (mixed solventof 2 parts by weight of tetrachloroethane and 3 parts by weight ofphenol, 25° C.). This prepolymer was formed into strand-like chips andsolid-phase polymerized under heating and vacuum to obtain athermoplastic polyester which was a solid-phase polymerization polymerhaving an intrinsic viscosity of 0.65 (mixed solvent of 2 parts byweight of trichlorophenol and 3 parts by weight of phenol, 35° C.).

Reference Example 2

An ester exchange reaction among 93 parts by weight of 2,6-naphthalenedicarboxylic acid dimethyl ester, 5.4 parts by weight of dimethylterephthalate and 70 parts by weight of ethylene glycol was carried outin the presence of cobalt acetate and manganese acetate as esterexchange catalysts while the by-produced methanol was distilled off tothe outside of a system and the temperature was increased to 250° C.,antimony trioxide was added as a polymerization catalyst when thedistillation of methanol was almost completed and phosphoric acid wasthen added as a stabilizer to terminate the ester exchange reaction.Thereafter, the reaction product was polycondensed under hightemperature and high vacuum to obtain a prepolymer having an intrinsicviscosity of 0.50 (mixed solvent of 2 parts by weight oftetrachloroethane and 3 parts by weight of phenol, 25° C.). Thisprepolymer was formed into strand-like chips and solid-phase polymerizedunder heating and vacuum to obtain a thermoplastic polyester which was asolid-phase polymerization polymer having an intrinsic viscosity of 0.70(mixed solvent of 2 parts by weight of trichlorophenol and 3 parts byweight of phenol, 35° C.).

Reference Example 3

An ester exchange reaction among 10 parts by weight of 2,6-naphthalenedicarboxylic acid dimethyl ester, 71.7 parts by weight of dimethylterephthalate and 70 parts by weight of ethylene glycol was carried outin the presence of cobalt acetate and manganese acetate as esterexchange catalysts while the by-produced methanol was distilled of f tothe outside of a system and the temperature was increased to 250° C.,antimony trioxide was added as a polymerization catalyst when thedistillation of methanol was almost completed and phosphoric acid wasthen added as a stabilizer to terminate the ester exchange reaction.Thereafter, the reaction product was polycondensed under hightemperature and high vacuum to obtain a prepolymer having an intrinsicviscosity of 0.57 (mixed solvent of 2 parts by weight oftetrachloroethane and 3 parts by weight of phenol, 25° C. ). Thisprepolymer was formed into strand-like chips and solid-phase polymerizedunder heating and vacuum to obtain a thermoplastic polyester which was asolid-phase polymerization polymer having an intrinsic viscosity of 0.83(mixed solvent of 2 parts by weight of tetrachloroethane and 3 parts byweight of phenol, 25° C.).

Reference Examples 4 and 5

An ester exchange reaction among 88 parts by weight of 2,6-naphthalenedicarboxylic acid dimethyl ester, 9.6 parts by weight of dimethylterephthalate and 70 parts by weight of ethylene glycol was carried outin the presence of cobalt acetate and magnesium acetate as esterexchange catalysts while the by-produced methanol was distilled off tothe outside of a system and the temperature was increased to 250° C.,antimony trioxide was added as a polymerization catalyst when thedistillation of methanol was almost completed and trimethyl phosphatewas then added as a stabilizer to terminate the ester exchange reaction.Thereafter, the reaction product was polycondensed under hightemperature and high vacuum to obtain a prepolymer having an intrinsicviscosity of 0.44 (mixed solvent of 2 parts by weight oftetrachloroethane and 3 parts by weight of phenol, 25° C.). Thisprepolymer was formed into strand-like chips and solid-phase polymerizedunder heating and vacuum to obtain a polymer (to be blended) having anintrinsic viscosity of 0.45 (mixed solvent of 2 parts by weight oftrichlorophenol and 3 parts by weight of phenol, 35° C.).

The polymer (to be blended) and PET (TR8580 of Teijin Limited (IV=0.83))were melt kneaded together in the following ratio to obtain athermoplastic polyester which was a blend polymer.

polymer (Reference Example 4); polymer (to be blended)/PET=30/70 (partsby weight)

polymer (Reference Example 5); polymer (to be blended)/PET=50/50 (partsby weight)

Examples 13 and 14 Production of Surface Coating Polyesters

Surface coating polyesters B and C were produced by the methods ofExamples 13 and 14 below.

Example 15 Surface Coating Polyester B

An ester exchange reaction among 87.5 parts by weight of dimethylterephthalate, 19 parts by weight of dimethyl 5-sodium sulfoisophthalic,12.5 parts by weight of dimethyl isophthalate, 72 parts by weight ofethylene glycol and 15.7 parts by weight of 2,6-naphthalene dimethylcarboxylate was carried out in the presence of manganese acetate andsodium acetate while the by-produced methanol was distilled off to theoutside of a system and the temperature was increased to 250° C.,antimony trioxide was added as a polymerization catalyst when thedistillation of methanol was almost completed and trimethyl phosphatewas then added as a stabilizer to terminate the ester exchange reaction.Thereafter, the obtained reaction product was polycondensed under hightemperature and high vacuum to obtain a polymer having an intrinsicviscosity of 0.35 (mixed solvent of 2 parts by weight oftetrachloroethane and 3 parts by weight of phenol, 25° C.). This polymerwas formed into strand-like chips to obtain surface coating polyester B.

Example 16 Surface Coating Polyester C

An ester exchange reaction among 46 parts by weight of dimethylterephthalate, 25 parts by weight of dimethyl 5-sodiumsulfoisophthalate, 19 parts by weight of dimethyl isophthalate, 72 partsby weight of ethylene glycol and 55 parts by weight of 2,6-naphthalenedimethyl carboxylate was carried out in the presence of manganeseacetate and sodium acetate while the by-produced methanol was distilledoff to the outside of a system and the temperature was increased to 250°C., antimony trioxide was added as a polymerization catalyst when thedistillation of methanol was almost completed and trimethyl phosphatewas then added as a stabilizer to terminate the ester exchange reaction.Thereafter, the obtained reaction product was polycondensed under hightemperature and high vacuum to obtain a polymer having an intrinsicviscosity of 0.30 (mixed solvent of 2 parts by weight oftetrachloroethane and 3 parts by weight of phenol, 25° C.). This polymerwas formed into strand-like chips to obtain surface coating polyester C.

Examples 17 to 24

A preform for a hollow molded product was injection molded from thepolyester of Reference Example 1, heated and formed into a bottle byorientation blow molding. The preform was molded by the M100DM moldingmachine of Meiki Co., Ltd. (cylinder temperature of 290° C., screwrevolution of 160 rpm, molding cycle of 30 sec). The preform had anaverage barrel thickness of 4.2 mm and a weight of about 55 g. Thebottle was molded by the LB01 of KRUPP CORPOPLAST Co., Ltd. and had aninner capacity of about 1.5 liters, an average barrel thickness of about300 μm and a haze of 0.7%.

Coating solutions 1 to 8 having compositions shown in Table 3 wereprepared. Any one of the coating solutions 1 to 8 was applied to theexterior surface of the above bottle and dried with air to form asurface coating layer as thick as about 1 μm to produce a bottle havingthe surface coating layer. The above test sample was cut out from thisbottle.

The test sample was exposed to ultraviolet radiation by the above methodand cleaned by the above method to remove the surface coating layer. Theoperation cycle of forming a surface coating layer again on the testsample in this state in the same manner as the first surface coatinglayer, exposing to ultraviolet radiation and cleaning was repeated atotal of 20 times.

After the above operation cycle was repeated 20 times, the haze of thetest sample after surface coating and the haze of the test sample aftercleaning were measured. The results are shown in Table 4.

At the time of first exposure to ultraviolet radiation, the exposed doseof ultraviolet radiation for one time of exposure was measured. Theresults are shown in Table 4.

The surface coating layer of the bottle having the first surface coatinglayer and the surface coating layer of the test sample could not beremoved with water (pH of 6.5) heated at 25° C. (35° C. or less) butcould be removed completely by the above cleaning.

Examples 25 to 28

Bottles were produced from the polyesters of Reference Examples 2 to 5in the same manner as in Example 1, a surface coating layer was formedon each of the bottles, and the resulting bottles having a surfacecoating layer were evaluated in the same manner as in Example 1. Theresults are shown in Tables 3 and 4.

The surface coating layer of the bottle having the first surface coatinglayer and the surface coating layer of the test sample could not beremoved with water (pH of 6.3) heated at 25° C. (35° C. or less) butcould be removed almost completely (about 90%) by the above cleaning.

TABLE 3 composition of coating solution (wt % based on the total weight)surface coating polyester surfactant solvent coating 10 wt % of surface2 wt % of polyethylene glycol 0.5 wt % of polyoxyethylene water solution1 coating polyester A (molecular weight of 200) sorbitan oleate coating15 wt % of surface 2 wt % of polyethylene glycol   1 wt % ofpolyoxyethylene water solution 2 coating polyester A (molecular weightof 300) sorbitan oleate coating 15 wt % of surface 2 wt % ofpolyethylene glycol — water solution 3 coating polyester A (molecularweight of 300) coating 10 wt % of surface —   1 wt % of polyoxyethylenewater solution 4 coating polyester A sorbitan oleate coating 15 wt % ofsurface — — water solution 5 coating polyester A coating 10 wt % ofsurface 2 wt % of polyethylene glycol 0.5 wt % of polyoxyethylenewater/ethanol = 4/1 solution 6 coating polyester A (molecular weight of200) sorbitan oleate coating 10 wt % of surface 2 wt % of polyethyleneglycol 0.5 wt % of polyoxyethylene water solution 7 coating polyester B(molecular weight of 200) sorbitan oleate coating 10 wt % of surface 2wt % of polyethylene glycol 0.5 wt % of polyoxyethylene water solution 8coating polyester C (molecular weight of 200) sorbitan oleate

TABLE 4 exposed dose haze after haze after of ultraviolet cleaningcoating radiation for one (%) (%) polyester surface time of exposure(after 20 times (after 20 times of bottle coating solution (mJ/cm²) ofrepetitions) of repetitions) Ex. 17 R. Ex. 1 coating solution 1 20,0003.7 0.9 Ex. 18 R. Ex. 1 coating solution 2 20,000 4.0 1.0 Ex. 19 R. Ex.1 coating solution 3 20,000 3.9 1.1 Ex. 20 R. Ex. 1 coating solution 420,000 3.9 1.6 Ex. 21 R. Ex. 1 coating solution 5 20,000 3.6 2.0 Ex. 22R. Ex. 1 coating solution 6 20,000 4.4 1.6 Ex. 23 R. Ex. 1 coatingsolution 7 20,000 4.5 1.4 Ex. 24 R. Ex. 1 coating solution 8 20,000 3.81.0 Ex. 25 R. Ex. 2 coating solution 1 20,000 3.0 0.5 Ex. 26 R. Ex. 3coating solution 1 20,000 2.8 0.8 Ex. 27 R. Ex. 4 coating solution 120,000 2.5 0.9 Ex. 28 R. Ex. 5 coating solution 1 20,000 2.0 0.6 C. Ex.1 R. Ex. 1 none 20,000 15.0 — Ex.: Example C. Ex.: Comparative ExampleR. Ex.: Reference Example

Comparative Example 1

A preform was injection molded from a polymer, heated and formed into abottle by orientation blow molding. The preform was molded by the M100DMmolding machine of Meiki Co., Ltd. (cylinder temperature of 290° C.,screw revolution of 160 rpm, molding cycle of 30 sec). The preform hadan average barrel thickness of 4.2 mm and a weight of about 55 g. Thebottle was molded by the LB01 of KRUPP CORPOPLAST Co., Ltd. and had aninner capacity of about 1.5 liters, an average barrel thickness of about300 μm and a haze of 0.7%. A coating layer was not formed.

The operation cycle of exposing the test sample to ultraviolet radiationby the above method and cleaning it by the above method was repeated 20times. After the above operation cycle was repeated 20 times, the hazeof the test sample was measured. The results are shown in Table 4.

At the time of first exposure to ultraviolet radiation, the exposed doseof ultraviolet radiation for one time of exposure was measured. Theresults are shown in Table 4.

Example 29

An ester exchange reaction among 100 parts by weight of dimethylterephthalate, 19 parts by weight of dimethyl 5-sodiumsulfoisophthalate, 12.5 parts by weight of dimethyl isophthalate and 72parts by weight of ethylene glycol was carried out in the presence ofmanganese acetate and sodium acetate while the by-produced methanol wasdistilled off to the outside of a system, antimony trioxide was added asa polymerization catalyst and the temperature was increased to 240° C.,and trimethyl phosphate was then added as a stabilizer when thedistillation of methanol was almost completed to terminate the esterexchange reaction.

Thereafter, the reaction product was polycondensed under hightemperature and high vacuum to obtain a polymer having an intrinsicviscosity of 0.37 (mixed solvent of 2 parts by weight oftetrachloroethane and 3 parts by weight of phenol, 25° C.), a Tg of 75°C. and a diethylene glycol content of 3.6 wt %. This polymer was formedinto strand-like pellets (cylindrical with a height of 3.5 mm, a shortdiameter of the bottom of 2.5 mm, a long diameter of the bottom of 3.5mm).

The pellet was used as a sample and evaluated by the following method.The results are shown in Table 5. Examples 30 to 42 and ComparativeExamples 3 and 4

Thermoplastic polyesters were obtained under conditions shown in Table 5and evaluated in the same manner as in Example 29.

TABLE 5 solubility in solubility in reduction in water heated waterheated intrinsic viscosity DMT DMI K2 NDC*1 DEG*2 intrinsic Tg at 95° C.at 30° C. caused by (mol %) (mol %) (mol %) (mol %) (wt %) viscosity (°C.) (%) (%) hydrolysis Ex. 29 80 10 10 0 3.6 0.37 75 25 0.3 0.005 Ex. 3080 10 10 0 6.7 0.45 65 30 0.3 0.007 Ex. 31 81.5 10 8.5 0 3.3 0.38 76 120.1 0.003 Ex. 32 81 10 9 0 3.8 0.39 74 15 0.2 0.004 Ex. 33 80.5 10 9.5 04.0 0.40 73 20 0.2 0.004 Ex. 34 77 10 13 0 8.5 0.40 60 30 0.8 0.006 Ex.35 89 0 11 0 5.5 0.35 70 25 0.6 0.006 Ex. 36 62 30 8 0 3.2 0.35 75 100.1 0.003 Ex. 37 70 10 10 10 6.5 0.40 73 15 0.3 0.003 Ex. 38 80 0 10 106.0 0.35 78 20 0.3 0.003 Ex. 39 45 15 10 30 7.5 0.30 88 18 0.2 0.004 Ex.40 25 10 15 50 7.2 0.28 95 15 0.7 0.006 Ex. 41 0 10 15 75 7.3 0.22 99 120.6 0.006 Ex. 42 5 0 13 82 7.5 0.20 103 11 0.3 0.003 C. Ex. 3 93 0 7 02.0 0.52 77 8 <0.1 0.003 C. Ex. 4 84 0 16 0 13 0.14 52 35 2 0.015 Ex.:Example C. Ex.: Comparative Example *1 NDC stands for 2,6-naphthalenedimethylcarboxylate *2 shows the content of diethylene glycolby-produced by polymerization reaction.

The glass transition temperature, solubility and reduction in intrinsicviscosity shown in Table 5were measured as follows.

Glass Transition Temperature (Tg):

10 mg of a thermoplastic polyester was used as a sample and its glasstransition temperature was measured by DSC at a temperature elevationrate of 5° C./min. solubility:

An excessive amount of a thermoplastic polyester pellet (cylindricalwith a height of 3.5 mm, a short diameter of the bottom of 2.5 mm and along diameter of the bottom of 3.5 mm) was dissolved in water to preparea solution of the thermoplastic polyester. The obtained solution was letpass through a 100 μm-mesh sieve to remove its solid matter. The amountof the thermoplastic polyester contained in the solution after the solidmatter was removed was obtained by subtracting (the amount of thethermoplastic polyester removed as solid matter) from (the amount of thethermoplastic polyester used) to calculate the maximum value ofconcentration (%) of the thermoplastic polyester in the solution. Thesolubilities in water heated at95° C. and water heated at 30° C. of thethermoplastic polyester were measured. reduction in intrinsic viscositycaused by hydrolysis:

This was calculated by subtracting (the intrinsic viscosity of athermoplastic polyester dissolved in water heated at 95° C. to aconcentration of 10% and maintained at 95° C. for 1 hour) from (theinitial intrinsic viscosity of the thermoplastic polyester dissolved inwater heated at 95° C. to a concentration of 10%).

As for the intrinsic viscosity of the thermoplastic polyester, theintrinsic viscosity of a sample which was dried up by removing waterwith a vacuum drier was measured.

Example 43

The polymer produced in Example 29 was dissolved in water heated at 95°C. to a concentration of 10 wt % to prepare a solution which was thenlet pass through 150 μm-mesh, 77 μm-mesh and 45 μm-mesh sievessequentially to produce a liquid composition. The evaluation results ofthe liquid composition are shown in Table 6.

This liquid composition was used to form a coating layer on a 380 mlbottle made from the polyethylene naphthalate resin (brand name; TN8065)of Teijin Limited by spray coating. This coating layer did not dissolvein water heated at 30° C. and did not peel off but was removed by 15minutes of cleaning with hot water heated at 75° C.

Examples 44 and 45

Thermoplastic polyesters having compositions shown in Table 6 wereobtained in the same manner as in Example 43 to produce liquidcompositions. The evaluation results of the liquid compositions areshown in Table 6.

Example 46

A thermoplastic polyester having composition shown in Table 6 wasobtained in the same manner as in Example 43 to produce a liquidcomposition. The evaluation results of this liquid composition are shownin Table 6.

This liquid composition was used to form a coating layer on a 380 mlbottle made from the polyethylene naphthalate resin (brand name; TN8065)of Teijin Limited by spray coating. This coating layer did not dissolvein water heated at 30° C. and did not peel off but was removed by 15minutes of cleaning with hot water heated at 75° C.

TABLE 6 liquid composition thermoplastic polyester solution electric DMTDMI K2 NDC*1 intrinsic Tg haze viscosity conductivity concentration (mol%) (mol %) (mol %) (mol %) viscosity (° C.) (%) (Pa · s) pH (μS/cm) (%)Ex. 43 80 10 10 0 0.37 75 8 0.01 5.6 840 10 Ex. 44 80 10 10 0 0.35 65 180.02 6.1 2100 12 Ex. 45 88 0 12 0 0.45 60 12 0.01 5.6 900 20 Ex. 46 0 1013 77 0.35 85 20 0.03 5.6 950 10 Ex.: Example *1 NDC stands for2,6-naphthalene dimethylcarboxylate.

Measurement items which are not described before in Table 6 were carriedout as follows.

Preparation of Liquid Composition:

A certain amount of a thermoplastic polyester was dissolved in hot waterheated at 95° C. . This solution was let pass through 150 μm-mesh, 77μm-mesh and 45 μm-mesh sieves sequentially to prepare a liquidcomposition. The concentration of the thermoplastic polyester in thisliquid composition was calculated from the content of the residual solidmatter by evaporating and drying up the solution.

Tinubin 234 (of Ciba Speciality Chem. Co., Ltd.) was dissolved inacetone or chloroform and mixed with the above polyester-containingsolution under agitation, and the resulting solution was graduallyheated at 95° C. to remove acetone or chloroform to prepare a liquidcomposition.

Haze:

The liquid composition was placed in a sampler and its haze was measuredby the Model 1001DP color and color difference meter of Nippon DenshokuKogyosha Co., Ltd.

pH:

The liquid polyester was placed in a sampler and its pH was measured bythe F-14 pH meter of HORIBA Co., Ltd. at 25° C.

Solution Viscosity:

The liquid composition was placed in a sampler and its solutionviscosity was measured by the Vismetron VS-A1 unicylindrical rotaryviscometer of Shibaura System Co., Ltd. at 25° C.

Electric Conductivity:

The liquid composition was placed in a sampler and its electricconductivity was measured by the CM-21P electric conductivity meter ofToa Denpa Kogyo Co., Ltd. at 25° C.

Example 47

Tinubin 234 (of Ciba Speciality Chem. Co., Ltd.) was dissolved inacetone to a concentration of 0.5 wt % to prepare a solution which wasthen mixed with the equivalent amount of the liquid composition ofExample 43 under agitation and gradually heated at 95° C. to removeacetone to prepare a liquid composition.

This liquid composition was used to form a coating layer on a 380 mlbottle made from the polyethylene naphthalate resin (brand name; TN8065)of Teijin Limited by spray coating. This coating layer did not dissolvein water heated at 30° C. and did not peel off but was removed by 15minutes of cleaning with hot water heated at 75° C.

The liquid composition was sprayed onto a chip of the polyethylenenaphthalate resin (brand name; TN8065) of Teijin Limited to form anultraviolet light absorbent-containing layer on the surface. A 380 mlbottle containing the ultraviolet light absorbent uniformly was formedfrom this chip.

Example 48

Tinubin 234 (of Ciba Speciality Chem. Co., Ltd.) was dissolved inchloroform to a concentration of 5 wt % to prepare a solution which wasthen mixed with the equivalent amount of the liquid composition ofExample 43 under agitation and gradually heated at 95° C. to removechloroform to prepare a liquid composition.

The polyethylene naphthalate resin (brand name; TN8065) of TeijinLimited was supplied from the top feed of a double-screw extruder having2 open vents and 2 vacuum vents and molten.

Subsequently, the above liquid composition was added to a molten portionof the resin by a quantitative injector. The open vents were disposedbefore and after the quantitative injector and water as a solvent wasremoved from these vents. The residual solvent and polyester decomposedgas were removed from the two vacuum vents and the resin was dischargedto a strand-like form to be formed into chip.

A380 ml bottle containing an ultraviolet light absorbent uniformly wasformed from this chip.

What is claimed is:
 1. A coated polyester hollow molded productcomprising: (A) a polyester hollow molded product, and (B) a polyestercoating layer formed on the exterior surface of the hollow moldedproduct, wherein said polyester coating layer (B) has a weight reductionof 3 wt % or less when it is treated with water at 25° C. for 2 hoursand is removed when it is treated with an alkali aqueous solution at 75°C. and having a pH of 11.6 for 9 minutes.
 2. The coated polyester hollowmolded product of claim 1 which has a haze value of 5% or less at athickness of 300 μm.
 3. The coated polyester hollow molded product ofclaim 1, wherein the polyester coating layer (B) has a thickness of 0.1to 10 μm.
 4. The coated polyester hollow molded product of claim 1,wherein the polyester coating layer (B) is made from a polyester whichcomprises 92.99 to 60 mol % of at least one dicarboxylic acid unitselected from the group consisting of naphthalene dicarboxylic acid unitand terephthalic acid unit, 0.01 to 20 mol % of an isophthalic acid unitand 7 to 20 mol % of an isophthalic acid unit having a sulfonic acidmetal salt group based on the total of all the dicarboxylic acid unitsas dicarboxylic acid components and 65 to 95mol % of an ethylene glycolunit and 35 to 5 mol % of a diethylene glycol unit based on the total ofall the diol units as diol units.
 5. The coated polyester hollow moldedproduct of claim 4, wherein the polyester of the polyester coating layer(B) is a polyester which comprises 8 to 15 mol % of an isophthalic acidunit having a sulfonic acid metal salt group based on the total of allthe dicarboxylic acid units and 75 to 95 mol % of an ethylene glycolunit based on the total of all the diol units.
 6. The coated polyesterhollow molded product of claim 5, wherein the polyester of the polyestercoating layer (B) is a polyester having a glass transition temperatureof 55 to 90° C.
 7. A solution for coating the surface of a polyesterhollow molded product of claim 4, which contains 1 to 40 wt % of thepolyester, 0.1 to 10 wt % of a surfactant and a liquid medium.
 8. Thesolution of claim 7, wherein the liquid medium consists essentially ofwater.
 9. The solution of claim 7 which has a haze value at 25° C. of30% or less, a pH of more than 5 and less than 7, a viscosity of 0.5Pa·s or less and an electric conductivity of 100 to 4,000 μS/cm.
 10. Thesolution of claim 7 which further contains at least one agent selectedfrom the group consisting of an ultraviolet light absorbent and acolorant.
 11. The coated polyester hollow molded product of claim 1,wherein the polyester of the polyester coating layer (B) has anintrinsic viscosity of 0.2 to 0.5.
 12. The coated polyester hollowmolded product of claim 1, wherein the polyester of the polyestercoating layer (B) contains an alkali metal compound in an amount of 10to 400 mmols based on 100 mols of the total of all the dicarboxylic acidcomponents.
 13. The coated polyester hollow molded product of claim 1,wherein the polyester of the polyester coating layer (B) has thefollowing properties (1), (2) and (3); (1) a solubility in water at 95°C. of 10 wt % or more, (2) a solubility in water at 30° C. of 1 wt % orless, and (3) a reduction in intrinsic viscosity after 1 hour of atreatment with water at 95° C. of 0.01 at maximum.
 14. The coatedpolyester hollow molded product of claim 1, wherein the polyestercoating layer (B) further contains a surfactant in an amount of 5 to 50parts by weight based on 100 parts by weight of the polyester.
 15. Thecoated polyester hollow molded product of claim 1, wherein the polyesterof the polyester hollow molded product (A) is polyethylene terephthalateor polyethylene-2,6-naphthalene dicarboxylate.
 16. A method ofregenerating a coated polyester hollow molded product, comprising thesteps of: preparing the salvaged coated polyester hollow molded productof claim 1, removing a polyester coating layer from the hollow moldedproduct, and forming a new polyester coating layer on the surface of thehollow molded product from which the polyester coating layer has beenremoved.
 17. The method of claim 16, wherein the removal of thepolyester coating layer is carried out using water or an alkali aqueoussolution at a temperature of 60 to 100° C.
 18. The method of claim 7,wherein a solution for coating the surface of a polyester hollow moldedproduct is applied to the surface of the hollow molded product and driedto form a new polyester coating layer, thereby forming a coatedpolyester hollow molded product comprising (A) a polyester hollow moldedproduct, and (B) a polyester coating layer formed on the exteriorsurface of the hollow molded product, wherein said solution for coatingthe surface of a polyester hollow molded product contains 1 to 40 wt %of a polyester which comprises 92.99 to 60 mol % of at least onedicarboxylic acid unit selected from the group consisting of naphthalenedicarboxylic acid unit and terephthalic acid unit, 0.01 to 20 mol % ofan isophthalic acid unit and 7 to 20 mol % of an isophthalic acid unithaving a sulfonic acid metal salt group based on the total of all thedicarboxylic acid units as dicarboxylic acid components and 65 to 95 mol% of an ethylene glycol unit and 35 to 5 mol % of a diethylene glycolunit based on the total of all the diol units as diol units, 0.1 to 10wt % of a surfactant and a liquid medium.